NO. 1580. NEW SPECIES OF CALIGIN.E— WILSON. 623 



separation of these two is indicated by a shallow constriction on either 

 side. This fused segment tapers posteriorly and terminates in a pair 

 of small anal laminse, nearly twice as witle as they are long. Each is 

 armed with five setge, one of which, the second from the inner edge, 

 is several times longer than the others. The first antennas are two- 

 jointed, the joints of the same size, the terminal one only with setae. 

 The second antennae are three-jointed, the terminal claw being slen- 

 der and weak. The mouth parts are practically the same as in the 

 adult; the terminal joint of the second maxillae is separated from 

 the basal even thus early by a well defined groove, and the rudimen- 

 tary endopod is carried on the basal joint. 



There are only two pairs of legs present, both biramose, with the 

 rami one-jointed. The endopod of the first pair is much smaller 

 than the exopod and destitute of setae; the two rami of the second 

 pair are the same size, but the endopod carries only a single seta. 

 Rudiments of the third and fourth legs appear as slight projections 

 on the ventral surface behind the first and second pairs. 



Total length, 0.76 mm.; length of carapace, 0.5 min.; greatest 

 width, 0.3 mm. 



Color a pale brownish gray, spotted over the entire dorsal surface 

 with brownish or purple pigment. The spots along the sides of the 

 digestive tube are fused into two prominent longitudinal lines, which 

 extend from the eyes nearly to the anus. 



This genus was obtained from the outside surface of the common 

 cobia or crabeater, Rachycentron canadus, and the outside surface of 

 the shark sucker Echeneis naucrates. The former specimens are taken 

 as the types since they include both sexes. The latter specimens are 

 Cat. No. 32806, U. S. N. M. 



Eight specimens of the chalimus were obtained from the fins of a 

 silver gar, Tylosaurus marinus, and are Cat. No. 32807, U. S. N, M. 

 The majority of these latter were on the tail fin, but one was taken 

 from the dorsal fin, another from the anal, and a third from one of 

 the pectorals. In each of these specimens the dorsal plates on the 

 fourth segment were formetl and projected from its lateral margins. 



The habits of the genus are quite similar to those of Caligus, with 

 which the presence of lunules in the frontal plates still further allies it. 

 But the females are not nearly as lively as those of Caligus and Lepe- 

 ophtheirus, and swim about very little, preferring to lie quietly at the 

 surface or near the bottom. The males, however, are very active and 

 move about restlessly all the time. Both sexes are hardy and live well 

 in confinement. 



The genus is of peculiar interest in that it forms another connecting 

 link between the Caliginae and the Euryphorinae. 



The presence of lunules and the simple form of the second maxillae 

 are characters of the genus Caligus. The divided furca and the clear 

 Proc. N. M. vol. xxxiii — 07 40 



